﻿// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

//JZlib 0.0.* were released under the GNU LGPL license.Later, we have switched
//over to a BSD-style license. 

//------------------------------------------------------------------------------
//Copyright (c) 2000-2011 ymnk, JCraft, Inc.All rights reserved.

//Redistribution and use in source and binary forms, with or without
//modification, are permitted provided that the following conditions are met:

//  1. Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.

//  2. Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in 
//     the documentation and/or other materials provided with the distribution.

//  3. The names of the authors may not be used to endorse or promote products
//     derived from this software without specific prior written permission.

//THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
//INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
//FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.IN NO EVENT SHALL JCRAFT,
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//NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
//EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// ReSharper disable ArrangeThisQualifier
// ReSharper disable InconsistentNaming
namespace DotNetty.Codecs.Compression
{
    using System;
    using DotNetty.Common.Utilities;

    /// <summary>
    ///  https://github.com/ymnk/jzlib/blob/master/src/main/java/com/jcraft/jzlib/InfTree.java
    /// </summary>
    sealed class InfTree
    {
        const int MANY = 1440;

        const int Z_OK = 0;
        //const int Z_STREAM_END = 1;
        //const int Z_NEED_DICT = 2;
        //const int Z_ERRNO = -1;
        //const int Z_STREAM_ERROR = -2;
        const int Z_DATA_ERROR = -3;
        const int Z_MEM_ERROR = -4;
        const int Z_BUF_ERROR = -5;
        //const int Z_VERSION_ERROR = -6;

        const int fixed_bl = 9;
        const int fixed_bd = 5;

        static readonly int[] fixed_tl =
        {
            96, 7, 256, 0, 8, 80, 0, 8, 16, 84, 8, 115,
            82, 7, 31, 0, 8, 112, 0, 8, 48, 0, 9, 192,
            80, 7, 10, 0, 8, 96, 0, 8, 32, 0, 9, 160,
            0, 8, 0, 0, 8, 128, 0, 8, 64, 0, 9, 224,
            80, 7, 6, 0, 8, 88, 0, 8, 24, 0, 9, 144,
            83, 7, 59, 0, 8, 120, 0, 8, 56, 0, 9, 208,
            81, 7, 17, 0, 8, 104, 0, 8, 40, 0, 9, 176,
            0, 8, 8, 0, 8, 136, 0, 8, 72, 0, 9, 240,
            80, 7, 4, 0, 8, 84, 0, 8, 20, 85, 8, 227,
            83, 7, 43, 0, 8, 116, 0, 8, 52, 0, 9, 200,
            81, 7, 13, 0, 8, 100, 0, 8, 36, 0, 9, 168,
            0, 8, 4, 0, 8, 132, 0, 8, 68, 0, 9, 232,
            80, 7, 8, 0, 8, 92, 0, 8, 28, 0, 9, 152,
            84, 7, 83, 0, 8, 124, 0, 8, 60, 0, 9, 216,
            82, 7, 23, 0, 8, 108, 0, 8, 44, 0, 9, 184,
            0, 8, 12, 0, 8, 140, 0, 8, 76, 0, 9, 248,
            80, 7, 3, 0, 8, 82, 0, 8, 18, 85, 8, 163,
            83, 7, 35, 0, 8, 114, 0, 8, 50, 0, 9, 196,
            81, 7, 11, 0, 8, 98, 0, 8, 34, 0, 9, 164,
            0, 8, 2, 0, 8, 130, 0, 8, 66, 0, 9, 228,
            80, 7, 7, 0, 8, 90, 0, 8, 26, 0, 9, 148,
            84, 7, 67, 0, 8, 122, 0, 8, 58, 0, 9, 212,
            82, 7, 19, 0, 8, 106, 0, 8, 42, 0, 9, 180,
            0, 8, 10, 0, 8, 138, 0, 8, 74, 0, 9, 244,
            80, 7, 5, 0, 8, 86, 0, 8, 22, 192, 8, 0,
            83, 7, 51, 0, 8, 118, 0, 8, 54, 0, 9, 204,
            81, 7, 15, 0, 8, 102, 0, 8, 38, 0, 9, 172,
            0, 8, 6, 0, 8, 134, 0, 8, 70, 0, 9, 236,
            80, 7, 9, 0, 8, 94, 0, 8, 30, 0, 9, 156,
            84, 7, 99, 0, 8, 126, 0, 8, 62, 0, 9, 220,
            82, 7, 27, 0, 8, 110, 0, 8, 46, 0, 9, 188,
            0, 8, 14, 0, 8, 142, 0, 8, 78, 0, 9, 252,
            96, 7, 256, 0, 8, 81, 0, 8, 17, 85, 8, 131,
            82, 7, 31, 0, 8, 113, 0, 8, 49, 0, 9, 194,
            80, 7, 10, 0, 8, 97, 0, 8, 33, 0, 9, 162,
            0, 8, 1, 0, 8, 129, 0, 8, 65, 0, 9, 226,
            80, 7, 6, 0, 8, 89, 0, 8, 25, 0, 9, 146,
            83, 7, 59, 0, 8, 121, 0, 8, 57, 0, 9, 210,
            81, 7, 17, 0, 8, 105, 0, 8, 41, 0, 9, 178,
            0, 8, 9, 0, 8, 137, 0, 8, 73, 0, 9, 242,
            80, 7, 4, 0, 8, 85, 0, 8, 21, 80, 8, 258,
            83, 7, 43, 0, 8, 117, 0, 8, 53, 0, 9, 202,
            81, 7, 13, 0, 8, 101, 0, 8, 37, 0, 9, 170,
            0, 8, 5, 0, 8, 133, 0, 8, 69, 0, 9, 234,
            80, 7, 8, 0, 8, 93, 0, 8, 29, 0, 9, 154,
            84, 7, 83, 0, 8, 125, 0, 8, 61, 0, 9, 218,
            82, 7, 23, 0, 8, 109, 0, 8, 45, 0, 9, 186,
            0, 8, 13, 0, 8, 141, 0, 8, 77, 0, 9, 250,
            80, 7, 3, 0, 8, 83, 0, 8, 19, 85, 8, 195,
            83, 7, 35, 0, 8, 115, 0, 8, 51, 0, 9, 198,
            81, 7, 11, 0, 8, 99, 0, 8, 35, 0, 9, 166,
            0, 8, 3, 0, 8, 131, 0, 8, 67, 0, 9, 230,
            80, 7, 7, 0, 8, 91, 0, 8, 27, 0, 9, 150,
            84, 7, 67, 0, 8, 123, 0, 8, 59, 0, 9, 214,
            82, 7, 19, 0, 8, 107, 0, 8, 43, 0, 9, 182,
            0, 8, 11, 0, 8, 139, 0, 8, 75, 0, 9, 246,
            80, 7, 5, 0, 8, 87, 0, 8, 23, 192, 8, 0,
            83, 7, 51, 0, 8, 119, 0, 8, 55, 0, 9, 206,
            81, 7, 15, 0, 8, 103, 0, 8, 39, 0, 9, 174,
            0, 8, 7, 0, 8, 135, 0, 8, 71, 0, 9, 238,
            80, 7, 9, 0, 8, 95, 0, 8, 31, 0, 9, 158,
            84, 7, 99, 0, 8, 127, 0, 8, 63, 0, 9, 222,
            82, 7, 27, 0, 8, 111, 0, 8, 47, 0, 9, 190,
            0, 8, 15, 0, 8, 143, 0, 8, 79, 0, 9, 254,
            96, 7, 256, 0, 8, 80, 0, 8, 16, 84, 8, 115,
            82, 7, 31, 0, 8, 112, 0, 8, 48, 0, 9, 193,

            80, 7, 10, 0, 8, 96, 0, 8, 32, 0, 9, 161,
            0, 8, 0, 0, 8, 128, 0, 8, 64, 0, 9, 225,
            80, 7, 6, 0, 8, 88, 0, 8, 24, 0, 9, 145,
            83, 7, 59, 0, 8, 120, 0, 8, 56, 0, 9, 209,
            81, 7, 17, 0, 8, 104, 0, 8, 40, 0, 9, 177,
            0, 8, 8, 0, 8, 136, 0, 8, 72, 0, 9, 241,
            80, 7, 4, 0, 8, 84, 0, 8, 20, 85, 8, 227,
            83, 7, 43, 0, 8, 116, 0, 8, 52, 0, 9, 201,
            81, 7, 13, 0, 8, 100, 0, 8, 36, 0, 9, 169,
            0, 8, 4, 0, 8, 132, 0, 8, 68, 0, 9, 233,
            80, 7, 8, 0, 8, 92, 0, 8, 28, 0, 9, 153,
            84, 7, 83, 0, 8, 124, 0, 8, 60, 0, 9, 217,
            82, 7, 23, 0, 8, 108, 0, 8, 44, 0, 9, 185,
            0, 8, 12, 0, 8, 140, 0, 8, 76, 0, 9, 249,
            80, 7, 3, 0, 8, 82, 0, 8, 18, 85, 8, 163,
            83, 7, 35, 0, 8, 114, 0, 8, 50, 0, 9, 197,
            81, 7, 11, 0, 8, 98, 0, 8, 34, 0, 9, 165,
            0, 8, 2, 0, 8, 130, 0, 8, 66, 0, 9, 229,
            80, 7, 7, 0, 8, 90, 0, 8, 26, 0, 9, 149,
            84, 7, 67, 0, 8, 122, 0, 8, 58, 0, 9, 213,
            82, 7, 19, 0, 8, 106, 0, 8, 42, 0, 9, 181,
            0, 8, 10, 0, 8, 138, 0, 8, 74, 0, 9, 245,
            80, 7, 5, 0, 8, 86, 0, 8, 22, 192, 8, 0,
            83, 7, 51, 0, 8, 118, 0, 8, 54, 0, 9, 205,
            81, 7, 15, 0, 8, 102, 0, 8, 38, 0, 9, 173,
            0, 8, 6, 0, 8, 134, 0, 8, 70, 0, 9, 237,
            80, 7, 9, 0, 8, 94, 0, 8, 30, 0, 9, 157,
            84, 7, 99, 0, 8, 126, 0, 8, 62, 0, 9, 221,
            82, 7, 27, 0, 8, 110, 0, 8, 46, 0, 9, 189,
            0, 8, 14, 0, 8, 142, 0, 8, 78, 0, 9, 253,
            96, 7, 256, 0, 8, 81, 0, 8, 17, 85, 8, 131,
            82, 7, 31, 0, 8, 113, 0, 8, 49, 0, 9, 195,
            80, 7, 10, 0, 8, 97, 0, 8, 33, 0, 9, 163,
            0, 8, 1, 0, 8, 129, 0, 8, 65, 0, 9, 227,
            80, 7, 6, 0, 8, 89, 0, 8, 25, 0, 9, 147,
            83, 7, 59, 0, 8, 121, 0, 8, 57, 0, 9, 211,
            81, 7, 17, 0, 8, 105, 0, 8, 41, 0, 9, 179,
            0, 8, 9, 0, 8, 137, 0, 8, 73, 0, 9, 243,
            80, 7, 4, 0, 8, 85, 0, 8, 21, 80, 8, 258,
            83, 7, 43, 0, 8, 117, 0, 8, 53, 0, 9, 203,
            81, 7, 13, 0, 8, 101, 0, 8, 37, 0, 9, 171,
            0, 8, 5, 0, 8, 133, 0, 8, 69, 0, 9, 235,
            80, 7, 8, 0, 8, 93, 0, 8, 29, 0, 9, 155,
            84, 7, 83, 0, 8, 125, 0, 8, 61, 0, 9, 219,
            82, 7, 23, 0, 8, 109, 0, 8, 45, 0, 9, 187,
            0, 8, 13, 0, 8, 141, 0, 8, 77, 0, 9, 251,
            80, 7, 3, 0, 8, 83, 0, 8, 19, 85, 8, 195,
            83, 7, 35, 0, 8, 115, 0, 8, 51, 0, 9, 199,
            81, 7, 11, 0, 8, 99, 0, 8, 35, 0, 9, 167,
            0, 8, 3, 0, 8, 131, 0, 8, 67, 0, 9, 231,
            80, 7, 7, 0, 8, 91, 0, 8, 27, 0, 9, 151,
            84, 7, 67, 0, 8, 123, 0, 8, 59, 0, 9, 215,
            82, 7, 19, 0, 8, 107, 0, 8, 43, 0, 9, 183,
            0, 8, 11, 0, 8, 139, 0, 8, 75, 0, 9, 247,
            80, 7, 5, 0, 8, 87, 0, 8, 23, 192, 8, 0,
            83, 7, 51, 0, 8, 119, 0, 8, 55, 0, 9, 207,
            81, 7, 15, 0, 8, 103, 0, 8, 39, 0, 9, 175,
            0, 8, 7, 0, 8, 135, 0, 8, 71, 0, 9, 239,
            80, 7, 9, 0, 8, 95, 0, 8, 31, 0, 9, 159,
            84, 7, 99, 0, 8, 127, 0, 8, 63, 0, 9, 223,
            82, 7, 27, 0, 8, 111, 0, 8, 47, 0, 9, 191,
            0, 8, 15, 0, 8, 143, 0, 8, 79, 0, 9, 255
        };

        static readonly int[] fixed_td =
        {
            80, 5, 1, 87, 5, 257, 83, 5, 17, 91, 5, 4097,
            81, 5, 5, 89, 5, 1025, 85, 5, 65, 93, 5, 16385,
            80, 5, 3, 88, 5, 513, 84, 5, 33, 92, 5, 8193,
            82, 5, 9, 90, 5, 2049, 86, 5, 129, 192, 5, 24577,
            80, 5, 2, 87, 5, 385, 83, 5, 25, 91, 5, 6145,
            81, 5, 7, 89, 5, 1537, 85, 5, 97, 93, 5, 24577,
            80, 5, 4, 88, 5, 769, 84, 5, 49, 92, 5, 12289,
            82, 5, 13, 90, 5, 3073, 86, 5, 193, 192, 5, 24577
        };

        // Tables for deflate from PKZIP's appnote.txt.
        static readonly int[] cplens =
        {
            // Copy lengths for literal codes 257..285
            3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
            35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0
        };

        // see note #13 above about 258
        static readonly int[] cplext =
        {
            // Extra bits for literal codes 257..285
            0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
            3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112 // 112==invalid
        };

        static readonly int[] cpdist =
        {
            // Copy offsets for distance codes 0..29
            1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
            257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
            8193, 12289, 16385, 24577
        };

        static readonly int[] cpdext =
        {
            // Extra bits for distance codes
            0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
            7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
            12, 12, 13, 13
        };

        // If BMAX needs to be larger than 16, then h and x[] should be uLong.
        const int BMAX = 15; // maximum bit length of any code

        int[] hn = null; // hufts used in space
        int[] v = null; // work area for huft_build 
        int[] c = null; // bit length count table
        int[] r = null; // table entry for structure assignment
        int[] u = null; // table stack
        int[] x = null; // bit offsets, then code stack

        int Huft_build(
            int[] b, // code lengths in bits (all assumed <= BMAX)
            int bindex,
            int n, // number of codes (assumed <= 288)
            int s, // number of simple-valued codes (0..s-1)
            int[] d, // list of base values for non-simple codes
            int[] e, // list of extra bits for non-simple codes
            int[] t, // result: starting table
            int[] m, // maximum lookup bits, returns actual
            int[] hp, // space for trees
            int[] hn, // hufts used in space
            int[] v // working area: values in order of bit length
        )
        {
            // Given a list of code lengths and a maximum table size, make a set of
            // tables to decode that set of codes.  Return Z_OK on success, Z_BUF_ERROR
            // if the given code set is incomplete (the tables are still built in this
            // case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of
            // lengths), or Z_MEM_ERROR if not enough memory.

            int a; // counter for codes of length k
            int f; // i repeats in table every f entries
            int g; // maximum code length
            int h; // table level
            int i; // counter, current code
            int j; // counter
            int k; // number of bits in current code
            int l; // bits per table (returned in m)
            int mask; // (1 << w) - 1, to avoid cc -O bug on HP
            int p; // pointer into c[], b[], or v[]
            int q; // points to current table
            int w; // bits before this table == (l * h)
            int xp; // pointer into x
            int y; // number of dummy codes added
            int z; // number of entries in current table

            // Generate counts for each bit length

            p = 0;
            i = n;
            do
            {
                c[b[bindex + p]]++;
                p++;
                i--; // assume all entries <= BMAX
            }
            while (i != 0);

            if (c[0] == n)
            {
                // null input--all zero length codes
                t[0] = -1;
                m[0] = 0;
                return Z_OK;
            }

            // Find minimum and maximum length, bound *m by those
            l = m[0];
            for (j = 1; j <= BMAX; j++)
                if (c[j] != 0)
                    break;
            k = j; // minimum code length
            if (l < j)
            {
                l = j;
            }
            for (i = BMAX; i != 0; i--)
            {
                if (c[i] != 0)
                    break;
            }
            g = i; // maximum code length
            if (l > i)
            {
                l = i;
            }
            m[0] = l;

            // Adjust last length count to fill out codes, if needed
            for (y = 1 << j; j < i; j++, y <<= 1)
            {
                if ((y -= c[j]) < 0)
                {
                    return Z_DATA_ERROR;
                }
            }
            if ((y -= c[i]) < 0)
            {
                return Z_DATA_ERROR;
            }
            c[i] += y;

            // Generate starting offsets into the value table for each length
            x[1] = j = 0;
            p = 1;
            xp = 2;
            while (--i != 0)
            {
                // note that i == g from above
                x[xp] = (j += c[p]);
                xp++;
                p++;
            }

            // Make a table of values in order of bit lengths
            i = 0;
            p = 0;
            do
            {
                if ((j = b[bindex + p]) != 0)
                {
                    v[x[j]++] = i;
                }
                p++;
            }
            while (++i < n);
            n = x[g]; // set n to length of v

            // Generate the Huffman codes and for each, make the table entries
            x[0] = i = 0; // first Huffman code is zero
            p = 0; // grab values in bit order
            h = -1; // no tables yet--level -1
            w = -l; // bits decoded == (l * h)
            u[0] = 0; // just to keep compilers happy
            q = 0; // ditto
            z = 0; // ditto

            // go through the bit lengths (k already is bits in shortest code)
            for (; k <= g; k++)
            {
                a = c[k];
                while (a-- != 0)
                {
                    // here i is the Huffman code of length k bits for value *p
                    // make tables up to required level
                    while (k > w + l)
                    {
                        h++;
                        w += l; // previous table always l bits
                        // compute minimum size table less than or equal to l bits
                        z = g - w;
                        z = (z > l) ? l : z; // table size upper limit
                        if ((f = 1 << (j = k - w)) > a + 1)
                        {
                            // try a k-w bit table
                            // too few codes for k-w bit table
                            f -= a + 1; // deduct codes from patterns left
                            xp = k;
                            if (j < z)
                            {
                                while (++j < z)
                                {
                                    // try smaller tables up to z bits
                                    if ((f <<= 1) <= c[++xp])
                                        break; // enough codes to use up j bits
                                    f -= c[xp]; // else deduct codes from patterns
                                }
                            }
                        }
                        z = 1 << j; // table entries for j-bit table

                        // allocate new table
                        if (hn[0] + z > MANY)
                        {
                            // (note: doesn't matter for fixed)
                            return Z_DATA_ERROR; // overflow of MANY
                        }
                        u[h] = q = /*hp+*/ hn[0]; // DEBUG
                        hn[0] += z;

                        // connect to last table, if there is one
                        if (h != 0)
                        {
                            x[h] = i; // save pattern for backing up
                            r[0] = (byte)j; // bits in this table
                            r[1] = (byte)l; // bits to dump before this table
                            j = i.RightUShift(w - l);
                            r[2] = q - this.u[h - 1] - j; // offset to this table
                            Array.Copy(r, 0, hp, (u[h - 1] + j) * 3, 3); // connect to last table
                        }
                        else
                        {
                            t[0] = q; // first table is returned result
                        }
                    }

                    // set up table entry in r
                    r[1] = (byte)(k - w);
                    if (p >= n)
                    {
                        r[0] = 128 + 64; // out of values--invalid code
                    }
                    else if (v[p] < s)
                    {
                        r[0] = (byte)(v[p] < 256 ? 0 : 32 + 64); // 256 is end-of-block
                        r[2] = v[p++]; // simple code is just the value
                    }
                    else
                    {
                        r[0] = (byte)(e[v[p] - s] + 16 + 64); // non-simple--look up in lists
                        r[2] = d[v[p++] - s];
                    }

                    // fill code-like entries with r
                    f = 1 << (k - w);
                    for (j = i.RightUShift(w); j < z; j += f)
                    {
                        Array.Copy(r, 0, hp, (q + j) * 3, 3);
                    }

                    // backwards increment the k-bit code i
                    for (j = 1 << (k - 1); (i & j) != 0; j = j.RightUShift(1))
                    {
                        i ^= j;
                    }
                    i ^= j;

                    // backup over finished tables
                    mask = (1 << w) - 1; // needed on HP, cc -O bug
                    while ((i & mask) != x[h])
                    {
                        h--; // don't need to update q
                        w -= l;
                        mask = (1 << w) - 1;
                    }
                }
            }
            // Return Z_BUF_ERROR if we were given an incomplete table
            return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
        }

        internal int Inflate_trees_bits(int[] c, // 19 code lengths
            int[] bb, // bits tree desired/actual depth
            int[] tb, // bits tree result
            int[] hp, // space for trees
            ZStream z // for messages
        )
        {
            int result;
            InitWorkArea(19);
            hn[0] = 0;
            result = Huft_build(c, 0, 19, 19, null, null, tb, bb, hp, hn, v);

            if (result == Z_DATA_ERROR)
            {
                z.msg = "oversubscribed dynamic bit lengths tree";
            }
            else if (result == Z_BUF_ERROR || bb[0] == 0)
            {
                z.msg = "incomplete dynamic bit lengths tree";
                result = Z_DATA_ERROR;
            }
            return result;
        }

       internal int Inflate_trees_dynamic(
           int nl, // number of literal/length codes
           int nd, // number of distance codes
           int[] c, // that many (total) code lengths
           int[] bl, // literal desired/actual bit depth
           int[] bd, // distance desired/actual bit depth 
           int[] tl, // literal/length tree result
           int[] td, // distance tree result
           int[] hp, // space for trees
           ZStream z // for messages
        )
        {
            int result;

            // build literal/length tree
            InitWorkArea(288);
            hn[0] = 0;
            result = Huft_build(c, 0, nl, 257, cplens, cplext, tl, bl, hp, hn, v);
            if (result != Z_OK || bl[0] == 0)
            {
                if (result == Z_DATA_ERROR)
                {
                    z.msg = "oversubscribed literal/length tree";
                }
                else if (result != Z_MEM_ERROR)
                {
                    z.msg = "incomplete literal/length tree";
                    result = Z_DATA_ERROR;
                }
                return result;
            }

            // build distance tree
            InitWorkArea(288);
            result = Huft_build(c, nl, nd, 0, cpdist, cpdext, td, bd, hp, hn, v);

            if (result != Z_OK || (bd[0] == 0 && nl > 257))
            {
                if (result == Z_DATA_ERROR)
                {
                    z.msg = "oversubscribed distance tree";
                }
                else if (result == Z_BUF_ERROR)
                {
                    z.msg = "incomplete distance tree";
                    result = Z_DATA_ERROR;
                }
                else if (result != Z_MEM_ERROR)
                {
                    z.msg = "empty distance tree with lengths";
                    result = Z_DATA_ERROR;
                }
                return result;
            }

            return Z_OK;
        }

        internal static int Inflate_trees_fixed(
            int[] bl, //literal desired/actual bit depth
            int[] bd, //distance desired/actual bit depth
            int[][] tl, //literal/length tree result
            int[][] td, //distance tree result 
            ZStream z //for memory allocation
        )
        {
            bl[0] = fixed_bl;
            bd[0] = fixed_bd;
            tl[0] = fixed_tl;
            td[0] = fixed_td;
            return Z_OK;
        }

        void InitWorkArea(int vsize)
        {
            if (hn == null)
            {
                hn = new int[1];
                v = new int[vsize];
                c = new int[BMAX + 1];
                r = new int[3];
                u = new int[BMAX];
                x = new int[BMAX + 1];
            }
            if (v.Length < vsize)
            {
                v = new int[vsize];
            }
            for (int i = 0; i < vsize; i++)
            {
                v[i] = 0;
            }
            for (int i = 0; i < BMAX + 1; i++)
            {
                c[i] = 0;
            }
            for (int i = 0; i < 3; i++)
            {
                r[i] = 0;
            }
            Array.Copy(c, 0, u, 0, BMAX);
            Array.Copy(c, 0, x, 0, BMAX + 1);
        }
    }
}
